From nobody Tue May 7 17:04:46 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=virtuozzo.com ARC-Seal: i=1; a=rsa-sha256; t=1616165787; cv=none; d=zohomail.com; s=zohoarc; b=IhhGFnh+SD4qoV+FxRikSlbYAvxwlKnu4UxXgS0H3wHMyVNahTEgsDZ+b34LtakkBVgUc8KPUgFVc9ccfXZhpWQ+PB2FHT/aQGFRtXXByI/p2tdREfINNsQQ23UK04ijxQzyYFoqhhqXv+Q3hKpp2o9SQvuKQOrMN/GToooayn8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1616165787; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=jH0WZ/RmDE/Z2aVjOBynPZMT/xmSLmwmRqUG0uuuXok=; b=Pwyi9g72kYWHZ5Gx7QpMlUW5nD2IP/8w5OQVRc8hcgxa440D8YRTNL/H8iZ/guJF+8s7NQ8sF+XNQ+OpPxZ1RsvO3JMLwGF+L31pKUwrsQ1t6SkDy+Ut1+RBdiEgKWPA8pilYaLiOkzgA78JAPyNN32s8WozDZuMzAYMcLRgVtQ= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1616165783904707.7224105373323; Fri, 19 Mar 2021 07:56:23 -0700 (PDT) Received: from localhost ([::1]:53218 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNGXz-0007aW-Pq for importer@patchew.org; Fri, 19 Mar 2021 10:56:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56518) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNGUn-00042y-Kq for qemu-devel@nongnu.org; Fri, 19 Mar 2021 10:53:02 -0400 Received: from relay.sw.ru ([185.231.240.75]:58480) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNGUh-0003xQ-0y for qemu-devel@nongnu.org; Fri, 19 Mar 2021 10:53:01 -0400 Received: from [192.168.15.248] (helo=andrey-MS-7B54.sw.ru) by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1lNGUX-00010K-SG; Fri, 19 Mar 2021 17:52:45 +0300 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=jH0WZ/RmDE/Z2aVjOBynPZMT/xmSLmwmRqUG0uuuXok=; b=B/6H6uU022Oo sbZPEslU4m+iauFlowAQ7EdXwGT+Kf62QWmrwQx2UZw9hB7gRGX5rNNjmKt0/OTVLo2kSdmDO2443 7wY6ijJAGPVSSWz6ZkT3H93/C5f+3fH5VduJYXyWx0x2aVhgEfy/mpF2e0jGivdo2aVY8wJ+k03d2 F7BL0=; From: Andrey Gruzdev To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Peter Xu , David Hildenbrand , Andrey Gruzdev Subject: [PATCH v1 1/3] migration: Fix missing qemu_fflush() on buffer file in bg_migration_thread Date: Fri, 19 Mar 2021 17:52:47 +0300 Message-Id: <20210319145249.425189-2-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210319145249.425189-1-andrey.gruzdev@virtuozzo.com> References: <20210319145249.425189-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay.sw.ru X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @virtuozzo.com) Content-Type: text/plain; charset="utf-8" Added missing qemu_fflush() on buffer file holding precopy device state. Increased initial QIOChannelBuffer allocation to 512KB to avoid reallocs. Typical configurations often require >200KB for device state and VMDESC. Signed-off-by: Andrey Gruzdev Reviewed-by: Peter Xu --- migration/migration.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/migration/migration.c b/migration/migration.c index ca8b97baa5..32b48fe9f5 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3812,7 +3812,7 @@ static void *bg_migration_thread(void *opaque) * with vCPUs running and, finally, write stashed non-RAM part of * the vmstate from the buffer to the migration stream. */ - s->bioc =3D qio_channel_buffer_new(128 * 1024); + s->bioc =3D qio_channel_buffer_new(512 * 1024); qio_channel_set_name(QIO_CHANNEL(s->bioc), "vmstate-buffer"); fb =3D qemu_fopen_channel_output(QIO_CHANNEL(s->bioc)); object_unref(OBJECT(s->bioc)); @@ -3866,6 +3866,8 @@ static void *bg_migration_thread(void *opaque) if (qemu_savevm_state_complete_precopy_non_iterable(fb, false, false))= { goto fail; } + qemu_fflush(fb); + /* Now initialize UFFD context and start tracking RAM writes */ if (ram_write_tracking_start()) { goto fail; --=20 2.25.1 From nobody Tue May 7 17:04:46 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=virtuozzo.com ARC-Seal: i=1; a=rsa-sha256; t=1616165891; cv=none; d=zohomail.com; s=zohoarc; b=AV0HLLA/RH972/co+VAKuC8omZazKIIs1TnD0+8lKKS3WUN7W0E5+9hUAzTsomgyKDZMktZrHfK9VidRdoEiNBRZMFLg6gDweUWi/NwsH5NAuwDUmbDmzK8YNlOQjzNEHoTJTIZX2gMMDft7OInI+D0WLI5SCA5KhEgmiBsPIPY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1616165891; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=KgHWLA8yy/gijf2EHgrj2T4u4/KRSoNyAnt0FgaqKKI=; b=DTg0rB8mKcw+c3SIdCHtFwU46Pe8oHlWYRiDqakFUqLjtGuIS9s+T8vxFB4ctnh3I7C+uxnnhMRoK4FUF8kVE7aX5Q7ZVcAdRKKfjZ+kKUK4D1sIsGEbdScUgzIAsClLjwRVvfLFlbBKxfH9qbBJKrfJFF5F6Erkl7C0dSIg/00= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1616165891265243.37563186282887; Fri, 19 Mar 2021 07:58:11 -0700 (PDT) Received: from localhost ([::1]:57908 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNGZm-00018T-6Z for importer@patchew.org; Fri, 19 Mar 2021 10:58:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56552) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNGUq-00045B-Ma for qemu-devel@nongnu.org; Fri, 19 Mar 2021 10:53:06 -0400 Received: from relay.sw.ru ([185.231.240.75]:58478) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNGUh-0003xO-1A for qemu-devel@nongnu.org; Fri, 19 Mar 2021 10:53:04 -0400 Received: from [192.168.15.248] (helo=andrey-MS-7B54.sw.ru) by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1lNGUX-00010K-V7; Fri, 19 Mar 2021 17:52:45 +0300 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=KgHWLA8yy/gijf2EHgrj2T4u4/KRSoNyAnt0FgaqKKI=; b=gZUo4NzCKM3x 37FhXWDfeLm70VEAG6mHdDy1BYE8qfdX0qRtNOD6s0Mz10CiNZ+b8oh6/vwkfkNnaIPsP9a1AC9xm uUIdqVtomRdfiSYlV9cbRV8jJUYLk+XlDswqSpazXUTPtfr7xARDx+hkZh8rHjJXRrYq6yBvSO154 +08x8=; From: Andrey Gruzdev To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Peter Xu , David Hildenbrand , Andrey Gruzdev Subject: [PATCH v1 2/3] migration: Inhibit virtio-balloon for the duration of background snapshot Date: Fri, 19 Mar 2021 17:52:48 +0300 Message-Id: <20210319145249.425189-3-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210319145249.425189-1-andrey.gruzdev@virtuozzo.com> References: <20210319145249.425189-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay.sw.ru X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @virtuozzo.com) Content-Type: text/plain; charset="utf-8" The same thing as for incoming postcopy - we cannot deal with concurrent RAM discards when using background snapshot feature in outgoing migration. Signed-off-by: Andrey Gruzdev Reviewed-by: David Hildenbrand Reviewed-by: Peter Xu --- hw/virtio/virtio-balloon.c | 8 ++++++-- include/migration/misc.h | 2 ++ migration/migration.c | 8 ++++++++ 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index e770955176..d120bf8f43 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -66,8 +66,12 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloone= dPage *pbp, =20 static bool virtio_balloon_inhibited(void) { - /* Postcopy cannot deal with concurrent discards, so it's special. */ - return ram_block_discard_is_disabled() || migration_in_incoming_postco= py(); + /* + * Postcopy cannot deal with concurrent discards, + * so it's special, as well as background snapshots. + */ + return ram_block_discard_is_disabled() || migration_in_incoming_postco= py() || + migration_in_bg_snapshot(); } =20 static void balloon_inflate_page(VirtIOBalloon *balloon, diff --git a/include/migration/misc.h b/include/migration/misc.h index bccc1b6b44..738675ef52 100644 --- a/include/migration/misc.h +++ b/include/migration/misc.h @@ -70,6 +70,8 @@ bool migration_in_postcopy_after_devices(MigrationState *= ); void migration_global_dump(Monitor *mon); /* True if incomming migration entered POSTCOPY_INCOMING_DISCARD */ bool migration_in_incoming_postcopy(void); +/* True if background snapshot is active */ +bool migration_in_bg_snapshot(void); =20 /* migration/block-dirty-bitmap.c */ void dirty_bitmap_mig_init(void); diff --git a/migration/migration.c b/migration/migration.c index 32b48fe9f5..32aee2c5bd 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1976,6 +1976,14 @@ bool migration_in_incoming_postcopy(void) return ps >=3D POSTCOPY_INCOMING_DISCARD && ps < POSTCOPY_INCOMING_END; } =20 +bool migration_in_bg_snapshot(void) +{ + MigrationState *s =3D migrate_get_current(); + + return migrate_background_snapshot() && + migration_is_setup_or_active(s->state); +} + bool migration_is_idle(void) { MigrationState *s =3D current_migration; --=20 2.25.1 From nobody Tue May 7 17:04:46 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=virtuozzo.com ARC-Seal: i=1; a=rsa-sha256; t=1616165882; cv=none; d=zohomail.com; s=zohoarc; b=E6iYLLLX6OhvuDLy9HpJfZ51eXZXW9JXQaaOLWkxnyr+doxlNq0awfKuL+j/PicqGT9+8P+n4SY/R2QZceFGvgvN5Wr9enUgzsOKco0eNMLE6lOFWsvdAu5Ybi65TQWja95dNQ48uBkig2bWqpE/gC265gjOTU9pPbo0eLbjiAQ= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1616165882; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=SimcNVQPEgM4Z6Pf9qEYCzmMBCppX5iXrLbgjb+2yio=; b=OKi2/xTfE9IGro5ap/nfMaWri78n2Syd53JNVRUCtPbvp+kZfNAVVMO4mSwTfvFER/MxHhJPtLZdWIQk+fJqLu+uKde7C7Hf3ybmxtSznSAzPfKde95suPBOTe5h8i7W4g/96NUysFwBYNQU+CNNn8yJAqUNN6r+ChWnVMhN0ho= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1616165882018509.9801044449267; Fri, 19 Mar 2021 07:58:02 -0700 (PDT) Received: from localhost ([::1]:57444 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNGZc-0000wh-NK for importer@patchew.org; Fri, 19 Mar 2021 10:58:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56574) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNGUs-000461-Ls for qemu-devel@nongnu.org; Fri, 19 Mar 2021 10:53:06 -0400 Received: from relay.sw.ru ([185.231.240.75]:58482) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNGUg-0003xP-W6 for qemu-devel@nongnu.org; Fri, 19 Mar 2021 10:53:06 -0400 Received: from [192.168.15.248] (helo=andrey-MS-7B54.sw.ru) by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1lNGUY-00010K-1o; Fri, 19 Mar 2021 17:52:46 +0300 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=SimcNVQPEgM4Z6Pf9qEYCzmMBCppX5iXrLbgjb+2yio=; b=rL8iBVLx/IfX KvfsaeK3XCuM3LJ3FPTzPlUqVHZv0JgSvGbM23DE1A2r7B8bbUTpTfk99l1MYEr81nTwwj0DwVlLq PRIG3TP81dm5Wz53atnqIJ5TO9N5Y+SNd7IBmSBAhs2Ys6o9IEcXONeJzQet3pgpRFDJH91okmwQu IrekQ=; From: Andrey Gruzdev To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Peter Xu , David Hildenbrand , Andrey Gruzdev Subject: [PATCH v1 3/3] migration: Pre-fault memory before starting background snasphot Date: Fri, 19 Mar 2021 17:52:49 +0300 Message-Id: <20210319145249.425189-4-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210319145249.425189-1-andrey.gruzdev@virtuozzo.com> References: <20210319145249.425189-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay.sw.ru X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @virtuozzo.com) Content-Type: text/plain; charset="utf-8" This commit solves the issue with userfault_fd WP feature that background snapshot is based on. For any never poluated or discarded memory page, the UFFDIO_WRITEPROTECT ioctl() would skip updating PTE for that page, thereby loosing WP setting for it. So we need to pre-fault pages for each RAM block to be protected before making a userfault_fd wr-protect ioctl(). Signed-off-by: Andrey Gruzdev Reviewed-by: Peter Xu --- migration/migration.c | 6 ++++++ migration/ram.c | 48 +++++++++++++++++++++++++++++++++++++++++++ migration/ram.h | 1 + 3 files changed, 55 insertions(+) diff --git a/migration/migration.c b/migration/migration.c index 32aee2c5bd..ae7855155f 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3827,6 +3827,12 @@ static void *bg_migration_thread(void *opaque) =20 update_iteration_initial_status(s); =20 + /* + * Prepare for tracking memory writes with UFFD-WP - populate + * RAM pages before protecting. + */ + ram_write_tracking_prepare(); + qemu_savevm_state_header(s->to_dst_file); qemu_savevm_state_setup(s->to_dst_file); =20 diff --git a/migration/ram.c b/migration/ram.c index 40e78952ad..24c8627214 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1560,6 +1560,54 @@ out: return ret; } =20 +/* + * ram_block_populate_pages: populate memory in the RAM block by reading + * an integer from the beginning of each page. + * + * Since it's solely used for userfault_fd WP feature, here we just + * hardcode page size to qemu_real_host_page_size. + * + * @bs: RAM block to populate + */ +static void ram_block_populate_pages(RAMBlock *bs) +{ + char *ptr =3D (char *) bs->host; + + for (ram_addr_t offset =3D 0; offset < bs->used_length; + offset +=3D qemu_real_host_page_size) { + char tmp =3D *(ptr + offset); + /* Don't optimize the read out */ + asm volatile("" : "+r" (tmp)); + } +} + +/* + * ram_write_tracking_prepare: prepare for UFFD-WP memory tracking + */ +void ram_write_tracking_prepare(void) +{ + RAMBlock *bs; + + RCU_READ_LOCK_GUARD(); + + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { + /* Nothing to do with read-only and MMIO-writable regions */ + if (bs->mr->readonly || bs->mr->rom_device) { + continue; + } + + /* + * Populate pages of the RAM block before enabling userfault_fd + * write protection. + * + * This stage is required since ioctl(UFFDIO_WRITEPROTECT) with + * UFFDIO_WRITEPROTECT_MODE_WP mode setting would silently skip + * pages with pte_none() entries in page table. + */ + ram_block_populate_pages(bs); + } +} + /* * ram_write_tracking_start: start UFFD-WP memory tracking * diff --git a/migration/ram.h b/migration/ram.h index 6378bb3ebc..4833e9fd5b 100644 --- a/migration/ram.h +++ b/migration/ram.h @@ -82,6 +82,7 @@ void colo_incoming_start_dirty_log(void); /* Background snapshot */ bool ram_write_tracking_available(void); bool ram_write_tracking_compatible(void); +void ram_write_tracking_prepare(void); int ram_write_tracking_start(void); void ram_write_tracking_stop(void); =20 --=20 2.25.1